Fix travis kyaml exit and targets

- properly exit non-0 if there are any uncommitted files
- make functions/examples targes
- add missing licenses
- refactor into loop

functions/examples/template-heredoc-cockroachdb/Makefile

@@ -7,6 +7,8 @@ license:
 	(which $(GOPATH)/bin/addlicense || go get github.com/google/addlicense)
 	$(GOPATH)/bin/addlicense  -y 2019 -c "The Kubernetes Authors." -f LICENSE_TEMPLATE .
 
+all: license
+
 image:
 	docker build image -t gcr.io/kustomize-functions/example-cockroachdb:v0.1.0
 	docker push gcr.io/kustomize-functions/example-cockroachdb:v0.1.0

functions/examples/validator-kubeval/image/Dockerfile

@@ -1,3 +1,6 @@
+# Copyright 2019 The Kubernetes Authors.
+# SPDX-License-Identifier: Apache-2.0
+
 FROM alpine:latest as schemas
 RUN apk --no-cache add git
 RUN git clone --depth 1 https://github.com/instrumenta/kubernetes-json-schema.git